The invention relates to an anti-theft plug or cap for a screw-threaded base of the type comprising a plate with a tapping corresponding to the threading of the base, a body rotatable in respect of the said plate, a securing element serving to render the said body integral with the said plate, and a cylindrical lock mounted in the said body and controlling the said securing element.
These known plugs suffer from the drawback that when the user screws the plug onto the base he risks applying an excessive final torque which may make it difficult to unscrew the plug and which may even result in damage to the screw threads and/or the securing element.
It has therefore been proposed, in order to eliminate this risk, that the securing element should be fitted with a torque limiting device, in such a way as to separate the rotary body and the plate when the tightening torque exceeds a certain value. The various proposals made for this purpose involve a number of disadvantages. In particular, they are too complicated and expensive to carry out or else necessitate eccentric mounting of the lock, which in certain cases, leads to problems regarding the space occupied by the apparatus.
The purpose of the present invention is to eliminate the drawbacks of the known plugs, by means of a new plug which will be simple and inexpensive to manufacture and assemble and which will enable the lock to be mounted non-eccentrically.